What was the treaty of 1492 that aimed to divide all of the America between Spain and Portugal?

The treaty you are referring to is the Treaty of Tordesillas, signed in 1494, not 1492. It was an agreement between Spain and Portugal, brokered by the Pope, that divided the newly discovered lands outside Europe between the two countries along a meridian 370 leagues west of the Cape Verde islands. This treaty aimed to resolve disputes over newly discovered territories and to prevent conflict between the two maritime powers during the Age of Exploration.